Rockford Fosgate 1501BD
So, I have been using this 1501BD for a couple of years now.
Here is my impression of the amp.
Lots of clean power
Can easily be modified to run 1ohm
Easily adjustable controls
Unfortunately, quite a few.
This amp requires a VERY strong power circuit.
Does not handle voltage drop well (at least mine doesn't)
With a drop in voltage, the amp would kick into a very annoying pulse/loop, only to stop when the system was de-activated.
With a less then perfect ground, you can run into some serious problems with this amp, from melting terminals to melting cables. I learned both, the hard way, and fortunately, before any fires.
Parts Availability, the mosfet strips are available, probably other random board pieces as well, but no longer are the terminals or end caps, making the previous issue that much more important to avoid.
Amp should likely have 1/0 Gauge power terminals, the four gauge just didn't seem to cut it when running it hard, and you should definitely have a second battery so you can use this to its full potential.
Price paid: $300USD used. They seem to go around this price on ebay frequently, definitely a good value, as long as you can support it.